The present invention relates to medical devices, and more particularly, to a laryngoscope guide and related methods of use.
Intubation is a medical procedure used by healthcare professionals to place an endotracheal tube in the trachea of a subject to facilitate breathing, or to permit controlled introduction of gases, such as oxygen or anesthetic gases, through the tube into the subject's airway. This medical procedure has evolved substantially over the years.
An early but still accepted and used intubation procedure is a direct viewing method, in which a professional tilts a subject's head posteriorly, with the subject's neck extended, and peers through the oral cavity, generally down the throat toward the trachea. To assist in viewing, a laryngoscope including a simple handle attached to a blade, is inserted in the mouth with the blade trapping and moving the subject's tongue and/or epiglottis out of the line of sight. This method generally requires that the professional align the oral axis, that is, the axis extending generally into the subject's mouth, with the laryngeal and pharyngeal axes, that is, the longitudinal axes generally corresponding to the subject's larynx and pharynx, respectively. In some cases, the professional also inserts a long, thin stylet or Bougie, independently of the laryngoscope, into the mouth and down through the vocal chords and into the trachea, all while directly viewing the advancement. With the stylet placed, the professional places a larger endotracheal tube over the stylet, and guides it with the Bougie to the trachea to establish an airway. The Bougie is then carefully removed.
Although this method serves its purpose, it can be difficult if not impossible to use on subjects who have abnormal airways, are obese, have undergone trauma requiring a cervical spine collar, have arthritis, have mandibular fractures, have had previous cervical fusion, or are combative. Examples of various stylet laryngoscopy procedures are disclosed in U.S. Pat. No. 4,865,586 to Hedberg, U.S. Pat. No. 5,235,970 to Augustine, as well as U.S. Pat. No. 6,820,614 and U.S. Pat. No. 7,320,319 to Bonutti; and U.S. Patent Publication 2008/0230056 to Boedeker.
Over time, laryngoscopy has implemented viewing devices to obtain an indirect view of the glottis to facilitate intubation. For example, with the advent of fiberoptics, laryngoscopes began to include, and many still do, fiberoptic bundles near the blade that enable a professional to view the subject's anatomy near the blade. Joined with the blade of such devices is a stylet located inside an endotracheal tube, also joined with the blade. In use, the stylet is viewed with the fiberoptics, inserted in the trachea, and the endotracheal tube is placed in the trachea. With the endotracheal tube in place, the laryngoscope blade, fiberoptics, light source and stylet are all simultaneously withdrawn, leaving the endotracheal tube and a related cuff in the airway. Although these devices also serve a purpose, one issue is that the blade, fiberoptics, light source, stylet and endotracheal are all located in the subject simultaneously, which can prove problematic, particularly where the airway is restricted, where the airway has already experienced trauma, or where the subject is obese. Examples of various fiberoptic laryngoscopes are the Bullard Scope disclosed in U.S. Pat. Nos. 5,551,946 and 5,665,052 to Bullard, as well as the laryngoscope disclosed in U.S. Pat. No. 6,146,402 to Munoz.
More recently, laryngoscopes have evolved to include a camera located adjacent the laryngoscope blade that feeds video or images to a viewing monitor attached to a handle of the laryngoscope. The image displayed on the monitor can be viewed by the professional during insertion of the endotracheal tube to assist in guiding the tube into the trachea. Examples of video laryngoscopes are the McGrath® video laryngoscope, available from Aircraft Medical Limited of Edinburgh, Great Britain, the GlideScope®, available from Verathon® Medical of Bothell, Wash., the Pentax AWS, available from Pentax Medical Company of Montvale, N.J., the Storz C-Mac, available from Karl Storz GmbH of Tuttlingen, Germany, and the Daiken Medical Coopdech C-Scope, available from Daiken Medical Co., Ltd of Osaka, Japan. Further examples of more recent viewing devices including laryngoscopes are disclosed in U.S. Pat. No. 5,827,178 to Berall; U.S. Pat. No. 6,652,453 to Smith; and U.S. Patent Publications 2003/0195390 to Graumann; 2007/0175482 to Kimmel; 2008/0177148 to Chen; 2008/0051628 to Pecherer and 2008/0312507 to Kim,
A potential issue with many video laryngoscopes is that they are designed to operate as a physically separate component from the endotracheal tube. For example, the blade of most standard video laryngoscopes is inserted first into the mouth and positioned to image the vocal chords and trachea so the professional can view these features on a viewing screen. Next, the endotracheal tube is placed in the mouth and forced toward the vocal chord opening, with the end of the tube eventually coming into view of the camera of the device. In such a procedure, the professional must blindly steer the tube from a point where they lose view of the tube in the mouth to the point where the end of the tube is picked up by the camera. In some cases, while being blindly steered, the tube may steer in the wrong direction, may get hung up on tissue (particularly in obese subjects), or may unintentionally abrade or agitate tissue in the region where it is blindly steered.
Further, even after the end of the endotracheal tube comes into view of the camera so it can be viewed by the professional on the screen, the tube can be difficult, and in some cases impossible, to steer into the trachea, particularly in subjects having difficult anatomy, where the professional is inexperienced or where the professional is rushed to get an airway established due to the condition of the subject. Some video laryngoscope manufacturers have attempted to address this inherent steering deficiency by providing a rigid, preformed rod over which the endotracheal tube is positioned before the tube is inserted in the airway, independently of the laryngoscope blade. The rigid rod can provide some degree of steering to the tube, which otherwise might be flexible. Even with the rigid rod in the tube, however, directing the endotracheal tube can be challenging and time consuming—which is usually unacceptable when every second counts in establishing an airway.
Other video laryngoscope manufacturers have attempted to develop a completely different solution to steer the endotracheal tube. For example, certain laryngoscopes have blades including independent and separated retaining clips. Some laryngoscopes have blades including an open groove in a lateral portion of the guide. In these constructions, the endotracheal tube is captured in the clips or the groove, and advanced with the blade into the subject's oral cavity toward the trachea. With the tube attached to the blade, the laryngoscope blade can be used to place the tube by manipulating to the blade. Of course, if the end of the endotracheal tube is to be moved substantially laterally, the blade likewise will be moved substantially laterally. In some cases, the blade may be restricted from such lateral movement due to a difficult anatomy or immobility of the subject.
Another issue with some laryngoscope guides including clips or grooves is that they can be difficult to use with endotracheal tubes including cuffs disposed at the end of the tubes. For example, the cuffs of many endotracheal tubes are delicate and can tear easily. Therefore, they are not well suited to advance through any type of groove. In addition, the cuff of these types of endotracheal tubes can present a viewing obstacle when they are placed beside or in front of a camera of the device. In some cases the cuff completely obscures the target toward which the endotracheal tube is advanced.
In addition, after a tube is placed with such a construction, the laryngoscope is separated from the endotracheal tube leaving the endotracheal tube in place. The separation of the tube from the blade is usually accomplished by wrenching the endotracheal tube laterally away from the blade. In some cases, this can be difficult, as it requires ample space within the anatomy of the airway to enable the tube to be separated from the blade. Many times, there simply is no such “extra” space. Moreover, in subjects with traumatized or damaged vocal chords or other tissue, this lateral movement of the endotracheal tube can complicate matters. Examples of various laryngoscopes including endotracheal tube retainers are disclosed in WO 2009/027672 (PCT/GB2008/002903) to McGrath and U.S. Patent Publication 2007/0106117 to Yokota.
Despite issues concerning endotracheal tube guidance, video laryngoscopes are becoming an increasingly used tool in performing laryngoscopy, particularly in obese and morbidly obese subject populations. Obese subjects typically have reduced functional residual capacity with decreased pulmonary oxygen stores, leading to rapid desaturation, which means that rapid intubation can be even more desirable in such subjects. Obese subjects also typically have a short neck, a large tongue and redundant folds of oropharyngeal tissue, which can make intubation difficult and can increase the risk of airway obstruction. Cattano, David et. al., Video Laryngoscopy in Obese Subjects, Anesthesiology News Guide to Airway Management, pp. 43-48 (September 2010). With video laryngoscopes, healthcare professionals can perform laryngoscopy on obese subjects with reduced risk for airway trauma or damage. Id at 45. However, the amount of time it takes to intubate obese patients with video laryngoscopes is a disputed limitation associated with the video laryngoscopes. Id. at 46.
Although laryngoscopy has evolved over the years, and is making use of current video technology, there still remains long felt and unmet needs to: reduce the amount of time to intubate subjects, for example, in obese subjects and subjects with difficult airways; to decrease potential damage and trauma to the airway; and to intubate in an efficient manner, even in cases where the professional does not have a significant amount of experience in performing the procedure. There also seems to be many attempted solutions to address this need, however, they all seem to fall short, and many seem to be pointing in different directions. For example, as noted above, some position endotracheal tubes separately from the laryngoscope and attempt to use rigid guides to guide the tubes, while others place the endotracheal tubes in grooves or clips of the laryngoscope in an attempt to direct the tube. Thus, it appears that many of the presently attempted solutions teach away from one another.